Internal combustion engines generally operate by compressing a fuel and air mixture then firing a spark that ignites the mixture to produce the controlled explosion that powers the engine. The spark is typically produced by sending a high voltage to a spark plug that has a specified gap size. The high voltage causes electrons to jump across the gap, and the resulting spark ignites the fuel. The efficiency and pollution characteristics of an internal combustion engine are determined in part by the completeness of burning the fuel. If an engine does not burn all of the fuel or fails to produce a spark so that none of the fuel is burned, the unburned fuel is expelled as exhaust from the vehicle using the internal combustion engine. Whether an engine completely burns the fuel is determined in part by the robustness of the spark. Years of research have gone into creating ever more durable and reliable spark generation systems to ensure reliable spark production. Modern ignition systems typically include platinum tipped spark plugs that can reliably produce a spark for 100,000 miles or more.
One area of research that has dramatically improved spark performance is the production of plasma at the spark gap of the spark plug. Plasma is ionization of the air around the gap to a point where the spark is no longer just between the two electrodes on either side of the spark plug gap, but is also in a ball of charge surrounding the gap. This larger spark produces a more complete burning of the fuel, and leads to more power and efficiency from the engine. While a spark is produced by high voltage that causes electrons to jump the spark plug gap, a plasma ionization is produced by feeding high current across the spark plug gap. Although a spark plug gap is initially an open circuit, once the spark crosses the gap the gap is a similar conductor to a wire, and a high current fed to the gap after the initial spark will result in plasma ionization.
Although typical ignition systems are good at generating high voltage, they are not typically designed to produce high current. Current plasma ignition systems therefore typically include a second power supply circuit that feeds the current used for plasma ionization. While the combined circuitry produces a much better spark, the increase in components and cost is a disadvantage of such dual energy ignition systems. A typical plasma ignition system includes two isolated DC-DC convert circuits the first DC DC converter circuit is a high voltage transformer that converts 12 VDC battery supply to generate a 20 to 80 KV ignition spark that ignites the fuel and the second DC DC converter, converts 12V DC battery to charge a 600V capacitor that discharges the follow on current to increase the energy of the ignition spark generated by the first DC DC converter circuit. This method results in additional components that increase the cost of the system and increase breakdown risk. In addition, modern ignition systems have moved to a coil-on-plug (COP) system that includes the traditional coil of a primary ignition system on top of the spark plug itself, to reduce radio frequency (RF) interference to other components of the vehicle and to reduce power loss inherent in transmitting a high voltage over a greater distance. For COP systems, it is difficult to fit a second power supply for high energy plasma ionization on top of the plug with the other electronics.